There are about 1000 species of spiders in the United States. They live everywhere, even inside homes and buildings. Some species are able to bite humans and inject a venom into the skin. The brown recluse and the widow spiders are considered venomous spiders; however, most spiders are not harmful to man.

Biology and Description

All spiders have eight legs and two body regions . They are predators, feeding primarily on insects and other arthropods. When feeding, spiders inject a digestive fluid into their prey, then suck up the digested food. They can survive for long periods of time without feeding. Some spiders have been kept alive for over two years without feeding.

Because spiders feed entirely on living insects or other animals, they may actively search for their prey, hide and wait for them to pass, or build webs to trap flying insects. Most web-spinning spiders build and abandon several webs per year. The webs are produced by glands on the spider's abdomen. The silk is a liquid which hardens when exposed to the air. Silk is used to construct webs, safety lines, and egg sacs, and is used as parachutes for traveling long distances.

Spiders reproduce by laying eggs in a silken egg sac. The egg sac is either carried around by the female or hidden in the web. Egg sacs of large spiders may contain several hundred eggs. The eggs hatch in about 2-3 weeks after they are deposited. Most young spiders mature to adults in about one year. Male and female spiders live separately and only come together to mate. Males are usually smaller and color-marked differently than females.

Almost all spiders found in Florida are harmless to humans and most species do not attempt to bite unless they are provoked. Spiders usually remain hidden and do not seek out and bite humans. Most spiders cannot penetrate the skin of a human with their fangs . Almost all spiders possess venom, but only a few are considered dangerous to humans.

Spiders are of interest since some invade homes, others are considered poisonous, and some larger species are raised as pets.

House Spiders

Several species of spiders enter houses and become a nuisance to the homeowner. Many people simply dislike spiders and cannot tolerate their presence. When numerous, spiders are annoying because they construct webs. Abandoned webs collect dust, resulting in cobwebs. However, spiders are considered beneficial because they feed on insect pests and other spiders.

Newly hatched spiders are tiny and easily enter homes through screens or around loose fitting doors and windows. Careful screening will keep larger spiders out of homes. If insects they eat are not plentiful, spiders are less likely to infest a home.

Poisonous Spiders

It is important to save any biting spider so it can be identified later. Most spider bites are not likely to be dangerous, but medical care and advice should be sought in each case.